南四湖浮游植群落与环境因子关系的pCCA分析

Partial Canonical Correspondence Analysis of Phytoplankton Community and Environmental Factors in Nansihu Lake

南四湖是南水北调东线工程的重要输水通道和调蓄湖泊,为了探讨其浮游植物群落特征及其与环境因子关系,文章于2018年5月和9月在南四湖布置了17个采样点进行浮游植物调查,同步采集水样,检测溶解氧、pH、总氮、总磷和高锰酸盐指数等水化指标,并采用典范对应分析(canonical correspondence analysis,CCA)和偏典范对应分析(partial CCA,pCCA)等多元统计方法,对比研究浮游植物的种类组成、季节变化及与环境因子的关系。研究结果显示:2次调查共采集到浮游植物204种(属),分属8门;5月和9月浮游植物平均丰度分别为1.10×106cells/L和1.43×106cells/L,平均生物量分别为2.21 mg/L和15.02 mg/L,9月生物量显著高于5月。CCA结果显示浮游植物存在明显的季节变化,而采用partial CCA方法在排除季节演替过程的影响后,可以确定影响浮游植物群落的主要环境因子是表征水体污染的高锰酸盐指数。此外,CCA和partial CCA结果存在差异,表明常规CCA分析难以更加精确地辨析环境因子对浮游植物群落的作用与影响。

In order to explore the characteristics of phytoplankton community and its relationship with environmental factors in the Nansi Lake,an important water transport channel for the South-to-North Water Diversion Project,an investigation for phytoplankton in May and September 2018 was carried out,and at the same time the water samples were collected to analyze the water parameters such as dissolved oxygen,pH,total nitrogen,total phosphorus and permanganate index.The species composition,seasonal variation and environmental factors of phytoplankton were studied by the multivariate statistical methods.The results showed that 204 species(genus)of phytoplankton were collected,belonging to 8 families;the average abundance of phytoplankton in May and September was 1.10×10~6 cells/L and 1.43×10~6 cells/L,respectively.The average biomass was 2.21 mg/L and 15.02 mg/L,respectively.The biomass in September was significantly higher than that in May.The relationship between phytoplankton community and environmental factors was further studied by canonical correspondence analysis(CCA)and partial CCA(pCCA).CCA analysis indicated that there were obvious seasonal changes in phytoplankton.Further,pCCA indicated:after excluding the effects of seasonal succession,the main environmental factors affecting phytoplankton community are permanganate index,which characterizes water pollution.In addition,the difference between the results of CCA and partial CCA indicates that it is difficult for the conventional CCA analysis to distinguish the effects of environmental factors more accurately on phytoplankton community.